TDP uses only one sample to do the test under unkown controlled evnironment. DXOMark's test is more scientific and accurate in general that shows 24-105L at 24mm is sharper thane 15-85 at 15mm side.

no it isn't, except if you only look at the image center. In the many images that I have seen, the 24-105 is way behind the 15-85 in the corners at 24mm equiv., except maybe stopped down to f/11 or so. Again, one can throw around numbers from DXO or TDP, but I'd rather trust my own eyes with real life pictures.